Organopolysiloxanes are of considerable interest since they have high thermooxidative stability, extreme low temperature flexibility and low temperature dependence of their physical constants. However, their mechanical properties, such as tensile strength, tear propagation strength and peel strength are usually inferior to those of organic polymers. In order to avoid this disadvantage, attempts have been made to modify organopolysiloxanes using organic compounds. These organic compounds are, in particular, compounds which contain aromatic or heterocyclic structural elements or contain functional groups, such as ester and amide radicals. Reference is made here, for example, to German Patent 14 45 357 (R. L. Merker, Dow Corning Corp.; published on Feb. 6, 1969) and R. L. Merker, M. J. Scott, G. G. Haberland, J. Polym. Sci.: Part A 2 (1964) 31, where dimethylsiloxane-phenylene copolymers are described. Copolymers containing siloxane and aliphatic and aromatic hydrocarbon blocks are disclosed in U.S. Pat. No. 3,051,684 (M. Morten and A. Rembaum, The Board of Directors of The University of Akron; published on Aug. 28, 1962) and U.S. Pat. No. 3,483,270 (E. E. Bostick, General Electric Co., published on Dec. 9, 1969 ), while siloxane copolymers containing aromatic ester and amide groups have been disclosed in German Patent 25 43 919 (M. Bargain, Rhone-Poulenc Ind.; published on May 27, 1987) and the corresponding U.S. Pat. No. 4,088,670 (published on May 9, 1987), U.S. Pat. No. 4,147,711 (published on Apr. 3, 1979), U.S. Pat. No. 4,213,914 (published on Jul. 23, 1980) and U.S. Pat. No. 4,275,184 (published on Jun. 23, 1981). Examples of poly(imidosiloxanes) are disclosed in H. Kuckertz, Makromol. Chem. 98 (1966) 101-8. In addition, V. Percec, J. Polym. Sci.: Part A 26 (1988) 2047-76 describes siloxane polymers containing stilbenes as side groups. Numerous attempts to modify polysiloxanes using organic compounds are known. Reference is further made in this respect to M. Wick, G. Kreis and F.-H. Kreuzer in Ullmanns Encyklopadie der technischen Chemie, (Ullmann's Encyclopedia of Industrial Chemistry), Verlag Chemie, Weinheim, 4th Edition, 1982, Vol. 21, pages 532 ff.
Therefore, it is an object of the present invention to provide thermoplastic siloxane elastomers. Another object of the present invention is to provide a process for preparing thermoplastic siloxane elastomers.